Cognitive competence is an important factor that contributes to quality of life. Although a number of generalizations can now be made about age related differences in adult cognition, relatively little is known about the substantial individual differences that are observed in adult cognition, and about how life style may mediate individual differences in developmental change. The overall purpose of the proposed research is to determine how one specific factor may affect cognitive functioning during adulthood. In particular, relationships between everyday activity and cognitive functioning of adults will be explored in the proposed research. The specific objectives are: 1) to refine and validate measures of everyday activity and everyday cognition; 2) to determine how everyday activities relate to cognitive functioning across adulthood; and 3) to determine what characteristics of everyday activities (e.g., mental challenges, physical challenges, complexity, diversity) account for observed relationships between everyday activity and cognitive functioning. The proposed project involves two phases of work. During the first, one year phase, procedures to measure everyday activities and everyday cognitive abilities will be refined. During the second, two year phase, two studies will be carried out to assess effects of age and everyday activities on adult cognition. The project involves comprehensive assessment of cognition, including assessment of cognitive abilities likely to show diverse developmental patterns. This feature of the research should result in a more complete, veridical, and balanced view of adult cognition and cognitive aging than presently exists. The project also involves over representation of optimally functioning individuals. This feature of the research should enhance understanding of peak levels of cognition, and successful patterns of cognitive aging, that are possible. In addition, the project includes assessment of a factor hypothesized to mediate cognitive aging. This feature of the research should provide information that is of both theoretical and practical import.